000 AXNT20 KNHC 110545 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT TUE AUG 11 2009 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... TROPICAL WAVE IS ALONG 27W FROM 9N TO 22N WITH A 1012 MB LOW ALONG THE WAVE NEAR 15N MOVING W NEAR 10 KT. SATELLITE IMAGERY INDICATES THE LOW/MID LEVEL CYCLONIC CIRCULATION REMAINS... HOWEVER UPPER LEVEL NORTHERLY WINDS ON THE E PERIPHERY OF AN UPPER LEVEL HIGH CENTERED NEAR 20N40W IS BRINGING DRY AIR ALOFT TO THE WESTERN SIDE OF THE WAVE THUS LIMITING SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 13N-16N BETWEEN 27W-30W. THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR SO. SEE THE TROPICAL WEATHER OUTLOOK UNDER AWIPS/WMO HEADERS MIATWOAT/ABNT20 KNHC FOR ADDITIONAL DETAILS. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 48W/49W S OF 18N MOVING W NEAR 10 KT. THE AXIS OF THE WAVE IS ORIENTED WITHIN A BROAD MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. HOWEVER THE LOW/MID LEVEL CLOUD CURVATURE SUGGESTS THE WAVE AXIS IS TILTED MORE NNW TO SSE. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 75 NM OF LINE FROM 17N45W TO 14N52W. TROPICAL WAVE IS FROM ALONG 59W/60W S OF 18N MOVING W NEAR 10 KT. THE SURFACE LOW IS NO LONGER DISCERNIBLE. THE AXIS OF THE WAVE IS ORIENTED WITHIN A BROAD MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. THE LOW/MID LEVEL CIRCULATION IS ILL DEFINED AS THIS WAVE MOVES OVER THE WINDWARD ISLANDS. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE 11N-14N BETWEEN 59W-62W INCLUDING THE WINDWARD ISLANDS AND BARBADOS. TROPICAL WAVE IS ALONG 74W S OF 15N MOVING W NEAR 15 KT. WAVE REMAINS EMBEDDED WITHIN AN AREA OF MODERATE ELY TRADES OVER THE CENTRAL CARIBBEAN AND CONTINUES TO BE DIFFICULT TO DISCERN ON SATELLITE IMAGERY. DUE TO DRY AND STABLE CONDITIONS ALOFT ACROSS THE CENTRAL CARIBBEAN THERE IS NO ASSOCIATED SHOWER ACTIVITY OR CONVECTION WITH THE WAVE. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 12N14W 15N24W 11N29W 11N43W 9N55W 11N60W TO INLAND OVER N VENEZUELA. SCATTERED MODERATE/ STRONG CONVECTION IS WITHIN 120 NM S OF THE ITCZ FROM 16W-19W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 6N-16N BETWEEN 14W-20W INCLUDING PORTIONS OF W AFRICA AND WITHIN 125 NM OF LINE FROM 11N28W 9N35W TO 8N45W. ...DISCUSSION... GULF OF MEXICO... A LARGE UPPER RIDGE ANCHORED OFF THE CAROLINA COAST EXTENDS S OVER THE W ATLC INCLUDING NE FLORIDA AND NE GULF N OF 28N E OF 87W. BROAD UPPER TROUGH DOMINATES MUCH OF THE REMAINDER OF THE GULF ANCHORED OVER THE YUCATAN PENINSULA WITH A SMALL AND WEAK UPPER HIGH ALONG THE NW GULF COAST NEAR THE LOUISIANA/TEXAS BORDER. UPPER DIFFLUENCE ACROSS THE CENTRAL GULF IS GENERATING ISOLATED SHOWERS ACROSS THE AREA FROM 23N-28N E OF 94W TO THE COAST OF FLORIDA WHILE A SURFACE TROUGH THAT EXTENDS FROM TAMPA FLORIDA SE TO 26N86W IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60 NM OF THE SURFACE TROUGH. SIMILAR SHOWERS/THUNDERSTORMS ARE IN THE E BAY OF CAMPECHE WITHIN 60 NM ALONG THE COAST OF THE YUCATAN S OF 20N E OF 94W. AT THE SURFACE...A 1019 MB HIGH IS OVER THE NE GULF JUST OFFSHORE NEAR PENSACOLA FLORIDA. CARIBBEAN SEA... BROAD UPPER UPPER TROUGH IS ANCHORED OVER THE YUCATAN NEAR THE N BORDER OF GUATEMALA COVERING THE W CARIBBEAN E OF 82W WITH DRY AIR ALOFT PROMOTING GENERALLY FAIR WEATHER ACROSS THE AREA WITH THE EXCEPTION OF OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN WITHIN 60 NM OF THE COAST OF HONDURAS. BROAD UPPER RIDGE COVERS THE REMAINDER OF THE CARIBBEAN ANCHORED NEAR 13N76W. MOIST SW UPPER FLOW BETWEEN THE W CARIBBEAN TROUGH AND CENTRAL CARIBBEAN RIDGE IS GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS S OF 16N W OF 80W AND OVER HAITI AND THE ADJACENT COASTAL WATERS. VERY DRY AIR ALOFT IS NOTED OVER MUCH OF THE CARIBBEAN REGION E OF 80W WITH THE EXCEPTION BEING ACROSS THE WINDWARD ISLANDS WHERE THE A TROPICAL WAVE IS MOVING INTO THE REGION. ATLANTIC OCEAN... THE UPPER RIDGE ANCHORED OFF THE CAROLINA COAST THAT COVERS THE FAR NE GULF OF MEXICO COVERS THE W ATLC N OF 22N W OF 60W WITH DRY AIR ALOFT SUPPRESSING ANY SHOWER ACTIVITY. HOWEVER...A NARROW UPPER TROUGH EXTENDS OVER THE CENTRAL ATLC WITH AXIS THROUGH 32N52W TO 23N65W. THIS UPPER TROUGH SUPPORTS A SURFACE TROUGH THAT EXTENDS FROM A WEAK 1015 MB LOW NEAR 31N62W TO 26N68W. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE FROM 27N-31N BETWEEN 57W AND THE SURFACE TROUGH. HIGH PRESSURE DOMINATES THE W ATLC INTO THE NE GULF OF MEXICO ANCHORED BY A 1021 MB HIGH NEAR 31N73W AND A SECOND SURFACE RIDGE OVER THE E ATLC ANCHORED BY A 1030 MB HIGH CENTERED NE OF THE AZORES. THE SURFACE RIDGE AXIS EXTENDS THROUGH 32N35W TO 27N53W. $$ WALLACE